Certain 4H- 1!benzopyrano 3,4-b!pyridine derivatives and their corresponding  6,7-b! and  7,8-b! ring isomers

ABSTRACT

The present invention relates to novel coumarin quinolone carboxylic acids wherein the pyridone system is fused in 3,4-, 6,7- and 7,8-positions of the coumarin system, of the general formula I ##STR1## wherein R 1  R 2  =--NHCH=C(CO 2  R 6 )CO, R 3  =NO 2  or NH 2 , R 4  =R 5  =H, R 6  =H or C 2  H 5  ; 
     R 1  R 2  =--NHCH=C(CO 2  R 6 )CO, R 3  =R 4  =H, R 5  =F, R 6  =H or C 2  H 5  ; 
     R 1  R 2  =--CO(CO 2  R 6 )C=CHNH, R 3  =R 4  =R 5  =H, R 6  =H or C 2  H 5  ; 
     R 1  R 2  =R 3  R 4  =--NHCH=C(CO 2  R 6 )CO, R 5  =H, R 6  =H or C 2  H 5  ; 
     R 1  =H or OH, R 2  =R 5  =H, R 3  R 4  =--NHCH (CO 2  R 6 )CO, R 6  =H or C 2  H 5  ; 
     R 1  =OH, R 2  =R 3  =H, R 4  R 5  =--CO(CO 2  R 6 ) C=CHNH, R 6  =H or C 2  H 5  ; 
     R 1  =R 5  =H, R 2  =CH 3  or CF 3 , R 3  R 4  =--CO(CO 2  R 6 )C=CHNH, R 6  =H or C 2  H 5 , 
     as well as pharmaceutically acceptable salts thereof. 
     The object of the invention are also processes for the preparation of novel coumarin quinolone carboxylic acids and the biological action thereof.

TECHNICAL FIELD

IPC: C07D 491/02

C07D 491/12

The present invention relates to novel coumarin quinolone carboxylic acids, wherein the pyridone system is fused in 3,4-, 6,7- and 7,8-positions of the coumarin system, of the general formula I ##STR2## wherein R¹ R² =--NHCH=C(CO₂ R⁶)CO--R³ =NO₂ or NH₂, R⁴ =R⁵ =H, R⁶ =H or C₂ H₅ ;

R¹ R² =--NHCH=C(CO₂ R⁶)CO--R³ =R⁴ =H, R⁵ =F, R⁶ =H or C₂ H₅ ;

R¹ R² =--CO(CO₂ R⁶)CHNH--=R³ =R⁴ =R⁵ =H, R⁶ =H or C₂ H₅ ;

R¹ R² =R³ R⁴ =NHCH=C(CO₂ R⁶) CO--R⁵ =H, R⁶ =H or C₂ H₅ ;

R¹ =H or OH, R² =R⁵ =H, R³ R⁴ =--NHCH =C(CO₂ R⁶)CO--R⁶ =H or C₂ H₅ ;

R¹ =OH, R² =R³ =H, R⁴ R⁵ =--CO(CO₂ R⁶) C=CHNH, R⁶ =H or C₂ H₅ ;

R¹ =R⁵ =H, R2=CH₃ or CF₃, R³ R⁴ =--CO(CO₂ R⁶)C=CHNH, R⁶ =H or C₂ H₅,

as well as pharmaceutically acceptable salts thereof.

The object of the invention are also processes for the preparation of the novel coumarin quinolone carboxylic acids as well as the biological action thereof.

According to the present invention novel coumarin quinolone carboxylic acids of the general formula I are prepared starting from coumarin malonate esters of the formula II disclosed in Croatian patent application P-960308A (European patent application No. . . . ) of Jul. 2, 1996 ##STR3## wherein R¹ =--NHCH=C(CO₂ C₂ H₅)₂,R² =R⁴ =H,R³ =H or NO₂, R⁵ =H or F;

R¹ =R³ =--NHCH=C(CO₂ C₂ H₅)₂, R² =R⁴ =R⁵ =H;

R¹ =H or OH, R³ =--NHCH=C(CO₂ C₂ H₅) ₂, R² =R⁴ =R⁵ =H;

R¹ =OH, R² =R³ =R⁴ =H, R⁵ =--NHCH=C(CO₂ C₂ H₅)₂ ;

R¹ =R³ =R⁵ =H, R² =CH₃ or CF₃, R⁴ =--NHCH=C(CO₂ C₂ H₅)₂,

which are heated in Dowtherm A at 250-260° C. for 10 minutes to 13 hours to obtain cyclized esters of the general formula III ##STR4## wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅) CO, R³ =R⁴ =H,R⁵ =F;

R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =NO₂, R⁴ =R⁵ =H;

R¹ R² =--CO(CO₂ C₂ H₅)C=CHNH, R³ =R⁴ =H, R⁵ =H or F;

R¹ R² =R³ R⁴ =--NHCH=C (CO₂ C₂ H₅)CO, R⁵ =H;

R¹ =H or OH, R² =R⁵ =H, R³ R⁴ =--NHCH =C(CO₂ C₂ H₅)CO;

R¹ =OH, R² =R³ =H, R⁴ R⁵ =--CO((CO₂ C₂ H₅)C=CHNH;

R¹ =R⁵ =H, R² =CH₃ or CF₃, R³ R⁴ =--CO((CO₂ C₂ H₅)C=CHNH.

For the compound of the formula III wherein R¹ R² =--CO ((CO₂ C₂ H₅)C=CHNH, R³ =R⁴ =H, R⁵ =H, it is expressly stated in D. T. Connor, P. A. Young, M. von Strandtman, J. Heterocyclic Chiem. 18 (1981) 697-702 that an attempt to cyclize the corresponding coumarin malonate ester to an ester of the formula III having the above mentioned substituents was unsuccessful and thus no corresponding acid was obtained either, said acid being, beside the ester of the formula III, also an object of the present invention and having the general formula I with the meanings R¹ R² =--CO(CO₂ H)C=CHNH, R³ =R⁴ =H, R⁵ =H.

The compound of the formula III wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =R⁴ =H, R⁵ =H (disclosed earlier in U.S. Pat. No. 4,210,758 to D. T. Connor (Warner-Lambert Company)) is at first nitrated, then reduced and finally fused with diethyl-ethoxymethylene malonate to obtain a compound of the formula IV ##STR5## wherein R=NO₂ or NH₂.

For obtaining the compounds of the general formula I wherein R¹ R² --NHCH=C (CO₂ C₂ H₅)CO, R³ =NH₂, R⁴ =R⁵ =H, the compounds of the general formula III wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =NO₂, R⁴ =R⁵ =H are reduced in glacial acetic acid under the catalyst palladium on active carbon and in a nitrogen stream of 3 bar for a time period of 6 hours. By the hydrolysis of the compounds of the formula III, coumarin quinolone carboxylic acids of the formula I are obtained, wherein R¹, R², R³, R⁴ and R⁵ have the earlier disclosed meanings and R⁶ =H.

Coumarin quinolone carboxylic acids, which are the object of the present invention, as well as pharmaceutically acceptable salts thereof are inhibitors of bacteria strains tested. In these tests a microdilution test for investigation of bacterial susceptibility according to the method NCCLS (M7-A2, Vol.10, No. 8, 1990; M100-S4, Vol. 12, No. 20, 1992) was used. Control test microorganisms employed in these experiments were S. aureus ATCC 29213, E. faecalis ATCC 29212 and P. aenrgiizosa ATCC 29213 with norfloxacin and enorfloxacin as working standards of antibiotics for comparison. The following strains were tested: Staphiloc. aureus ATCC 6538P, Bacillus subtilis NCTC 8236, Micrococcus flavus ATCC 10240, Pseudomonias aerug. NCTC 10490, Salmoizela Panama 6117, E. coli Lac+6131, E. coli Lac-6130, b-Haemol. streptococc. --B J-22, b-Haemol. streptococc. --A J-21, Streptococcus pyogenes 20F, Streptococcus faecalis ATCC 8043, E. coli ATCC 10536, Stapliyloc. epidermis ATCC 12228, B. cereus AYCC 11778, B. pumilus ATCC 8241 and B. subtilis ATCC 6633.

4,5-dihydro-4,5-dioxo- 1H- 1!benzopyrano 4,3-b!pyridine-3-carboxylic acid inhibited E. coli Lac+6131 and b-Haemol. streptococc. --A J-21.

1,5-dihydro-1,5-dioxo-7-fluoro-4H- 1!benzopyrano 3,4-b!pyridine-3-carboxylic acid inhibited the strains tested.

4,7-dihydro-4,7-dioxo-1H- 1!benzopyrano 6,7-b!pyridine-3-carboxylic acid inhibited Bacillus subtilis NCTC 8236, Streptococcus pyogeizes 20F and Streptococcus faecalis ATCC 8043.

Coumarin quinolone acids according to the present invention and pharmaceutically acceptable salts thereof were also investigated for an iil vitro antitumour action. The antitumour action was tested on the growth of cell lines of mammary cancer (MCF7), cancer of cervix uteri (HeLa), pancreas cancer (MiaPaCa2), larinx cancer (Hep2) and on normal human fibroblasts (Hef522).

1,7-dihydro-1,7-dioxo-9-(trifluoromethyl)-4H- 1!benzopyrano 6,7-b!pyridine-3-carboxylic acid inhibited the growth of the cells of mammary cancer (MCF7), pancreas cancer (MiaPaCa2) and larinx cancer (Hep2) and slightly stimulated the growth of cells of cancer of cervix uteri (HeLa) in higher concentrations. It had no significant action on the growth of fibroblasts (Hef522).

The MCF7 growth was inhibited depending on the concentration and the best inhibition was achieved at 10⁻⁵ and 10⁻⁸ M.

It had no effect on the growth of HeLa cells in the concentration range from 10⁻⁸ to 10⁻⁶ M, whereas at higher concentrations (10⁻⁵ and 10⁻⁴ M) it stimulated their growth.

The growth of MiaPaCa2 cells was inhibited depending on the concentration. At the concentration of ₁₀ ⁻⁴ M the attained inhibition was 35%.

The tested substance inhibited the growth of Hep2 cells, with increased concentration the inhibitory action was decreased and the best results were achieved in the concentration ranges of 10⁻⁷ and 10⁻⁵ M.

The tested substance exhibited no effect on the growth of normal fibroblasts (Hef522).

The invention is illustrated by the following Examples, which in no way should be construed as limitative.

EXAMPLE 1

Ethyl-1,5-dihydro- 1,5-dioxo-7-fluoro-4H- 1!benzopyrano 3,4-b!pyridine-2carboxylate ##STR6##

A solution of diethyl-{ (8-fluoro-2-oxo-2H- 1!-benzopyrano-3-yl) amino!-methylene} malonate (2.40 g; 0.871 mmole) in Dowtherm A (55 ml) was heated for 40 minutes at the boiling temperature. Into the cooled solution a petroleum ether having a low boiling point was added to assist with a complete precipitation of the obtained ester. The obtained precipitate of ethyl-1,5-dihydro-1,5-dioxo-7-fluoro-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylate of a gray brown colour was washed first with petroleum ether and then with diethyl ether (1.85 g; 89%). M.p.: 288-290° C.

Analysis: calculated for C₁₅ H₁₀ FNO₅ : C 59.41H 3.32N 4.62. found C 59.74H 2.97N 4.72.

¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (t, CH₃); 4.3 (q, CH₂); 6.8-7.6 (m, Ar H); 8.3 (s, Py H); 9.3 (d, NH).

EXAMPLE 2

Ethyl-4,5-dihydro-4,5-dioxo-1H- 1!-benzopyrano 3,4-b!pyridine-3-carboxylate ##STR7##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (2-oxo-4H- 1!-benzopyrano-3-yl)amino!methylene} malonate (3.96 g; 0.012 mole). Duration of the reaction: 13 hours. Ethyl-4,5-dihydro-4,5-dioxo-1H- 1!-benzopyrano 3,4-b!pyridine-3-carboxylate (1.90 g; 56%) was obtained.

Analysis: calculated for C₁₁ H₁₅ NO₅ : C 63.16; H 3.89; N 4.91. found C 62.98; H 3.92; N 5.07. ¹ H-NMR (TFA)δ/ppm: 1.2(t, CH₃); 4.3 (q, CH₂); 7.3-8.0 (m, Ar H); 8.4 (s, Py H); 11.3(s, NH).

EXAMPLE 3

Diethyl-1,5,8-trihydro-1,5,8-trioxo-4, 11H- 1!-benzopyrano 3,4-b!- 7,6-c!dipyridine-2,9-dicarboxylate ##STR8##

It was prepared according to the method disclosed in Example 1 starting from tetraethyl-{ (2-oxo-2H- 1!-benzopyrano-3,6-diyl)diamino!dimethylene } malonate (2.00 g; 3.872 mole). Duration of the reaction: 50 minutes. The obtained diethyl-1,5,8-trihydro-1,5,8-trioxo-4,11H- 1!-benzopyrano 3,4-b! 7,6-c!dipyridine-2,9-dicarboxylate of brown colour was recrystallized from absolute ethanol (1.43 g; 87%). M.p.: 175-177° C.

Analysis: calculated for C₂₁ H₁₆ N₂ O₅ C 59.43; H 3.80; N 6.60. found C 59.72; H 3.89; N 6.89. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (2t, 2 CH₃); 4.2 (2 q, 2 CH₂); 7-10 (m, CH, Ar H, Py H); 10.6 and 12.3 (2 d, 2 NH).

EXAMPLE 4

Ethyl-4,7-dihydro-4,7-dioxo-1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylate ##STR9##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (2-oxo-2H- 1!-benzopyrano-3-yl)amino!methylene} malonate (3.10 g; 9.357 mmole). Duration of the reaction: 45 minutes. The obtained yellow brown precipitate of ethyl-4,7-dihydro-4,7-dioxo- 1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylate was recrystallized from N,N-dimethylformamide (2.23 g; 84%). M.p. >300° C.

Analysis: calculated for C₁₅ H₁₁ NO₅ C 63.16; H 3.89; N 4.91. found C 63.05; H 3.92; N 4.88. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (t, CH₃); 4.2 (q, CH₂); 6.5 (d, H8), 7.4-8.0. (m, Ar H, Py H); 8.4 (d, H9); 10.7 (d, NH). m/z: 284 (M⁻), 258, 256, 239, 212, 183, 127, 79.

EXAMPLE 5

Ethyl-4,7-dihydro-4,7-dioxo-3-hydroxy- H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylate ##STR10##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (3-hydroxy-2-oxo-2H- 1!-benzopyrano-6-yl)aminojmethylene} malonate (3.63 g; 0.011 mole). Duration of the reaction: 15 minutes. A light yellow brown precipitate of ethyl-4,7-dihydro-4,7-dioxo-3-hydroxy- 1H- 1!-benzopyrano 6,7-b! pyridine-3-carboxylate (3.63 g; 95%) was obtained. M.p. >300° C.

Analysis: calculated for C₁₅ H₁₁ NO₆ C 59.80; H 3.68; N 4.65. found C 59.66; H 3.61; N 4.27. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (t, CH₃); 4.2 (q, CH₂); 7.2-9.3 (m, Ar H, Py H); 10.7 (s, OH); 12.4 (s, NH). m/z: 300 (M⁻), 273, 272, 255, 227, 178, 136, 91, 68, 54.

EXAMPLE 6

Ethyl-1,7-dihydro-1,7-dioxo-9-methyl-4H- 1!-benzopyrano 6,7-b!pyridine-2-carboxylate ##STR11##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (4-methyl-2-oxo-2H- 1!-benzopyrano-7-yl)amino!methylene } malonate (5.70 g; 0.017 mole). Duration of the reaction: 10 minutes. A gray brown precipitate of ethyl-1,7-dihydro-1, 7-dioxo-9-methyl-4H- 1 !-benzopyrano 6,7-b!pyridine-2-carboxylate (3.43 g; 69%) was obtained. M.p. >300° C.

Analysis: calculated for C₁₆ H₁₃ NO₅ C 64.21; H 4.38; N 4.68. found C 64.36; H 4.14; N 4.50. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (s, CH₃); 2.1 (t, CH₃); 4.1 (q, CH₂); 6.2 (d, H8); 7.4 (d, H5); 7.7 (t, H10); 10.3 (s, Py H); 12.4 (bs, NH).

EXAMPLE 7

Ethyl-4,7-dihydro-4,7-dioxo-9-(trifluromethyl)-1H- 1!-benzopyrano 6,7-b!-pyridine-2-carboxylate ##STR12##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (4-(trifluoromethyl)-2-oxo-2H-1!-benzopyrano-7-yl)amino!methylene} malonate (2.00 g; 0.005 mole). Duration of the reaction: 15 minutes. A light yellow precipitate of the ester (1.67 g; 94%) was obtained. M.p. >300° C.

Analysis: calculated for C₁₆ H₁₀ F₃ NO₅ C 54.40; H 2.85; N 3.97. found C 54.41; H 2.97; N 3.86. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (t, CH₃); 4.2 (q, CH₂); 7.0 (d, H8); 7.4 (s, H5); 7.9 (d, H10); 8.5 (d, Py H); 12.4 (bs, NH).

EXAMPLE 8

Ethyl-1,6-dihydro-1,6-dioxo-7-hydroxy-4H- 1!-benzopyrano 7,8-b!pyridine-2-carboxylate ##STR13##

It was prepared according to the method disclosed in Example 1 starting from diethyl-{ (3-hydroxy-2-oxo-2H- 1!-benzopyrano-8-yl)amino!methylene} malonate (3.15 g; 9.070 mole). Duration of the reaction: 40 minutes. Ethyl-1,6-dihydro-1,6-dioxo-7-hydroxy-4H- 1!-benzopyrano 7,8-b!pyridine-2-carboxylate of orange brown colour (2.35 g; 86%) was obtained. M.p. >300° C.

Analysis: calculated for C₁₅ H₁₁ NO₆ C 59.80; H 3.68; N 4.65. found C 59.45; H 3.29; N 4.28. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.3 (t, CH₃); 4.2 (q, CH₂); 7.1-8.3 (m, Ar H, Py H); 10.4 (s, OH); 11.8 (s, NH). m/z: 302 (M⁺), 171, 155, 141.

EXAMPLE 9

Ethyl-1,5-dihydro1,5-dioxo-9-nitro-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylate ##STR14##

To a solution of ethyl-1,5-dihydro-1,5-dioxo-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylate (0.81 g; 2.840 mmole) in concentrated sulfuric acid (3.73 g; 0.038 mole) which was cooled to 0-5° C., a mixture of nitric acid (d=1.4; 1.01 g; 0.016 mole) and concentrated sulfuric acid (1.96 g; 0.020 mole) was added drop by drop under stirring. The reaction mixture was stirred for another 10 minutes after attaining room temperature and then it was poured to a water-ice mixture. The obtained ethyl-1,5-dihydro-1,5-dioxo-9-nitro-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylate was recrystallized from ethanol (0.89 g; 95%). M.p.: 246-247° C.

Analysis: calculated for C₁₅ ; H₁₀ N₂ O₇ C 54.55; H 3.05; N 8.48. found C 54.50; H 2.87; N 8.65. ¹ H-NMR (TFA)δ/ppm: 1.2 (t, CH₃); 4.3 (q, CH₂); 7.4 (d, H7); 8.3 (d, H8); 9.1 (s, H10); 9.6 (s, Py H); 11.3 (s, NH). m/z: 329 (M⁻), 313, 301, 284, 269, 257, 256, 241, 228, 151.

EXAMPLE 10

Ethyl1,5-dihydro1,5-dioxo-9-amino-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylate ##STR15##

To a solution of ethyl-1,5-dihydro-1,5-dioxo-9-nitro-4H- 1!-benzopyrano 3,4-b!-pyridine-2-carboxylate (0.50 g; 1.514 mmole) in glacial acetic acid (150 ml) a catalyst (4.92% Pd/C; 0.15 g) was added and the reduction took place for 6 hours under hydrogen stream of 3 bar. After the completion of the reaction acetic acid was evaporated from the filtered reaction mixture. The obtained amine (0.59 g; 100%) was recrystallized from glacial acetic acid. M.p.: 270-272° C.

Analysis: calculated for C₁₅ H₂₂ N₂ OxC₂ H₄ O₂ C 58.18; H 4.28; N 8.48. found C 57.94; H 4.14; N 8.24. ¹ H-NMR (TFA)δ/ppm: 1.3 (t, CH₃); 4.4 (q, CH₂); 7.4-7.8 (m, Ar H); 9.2 (m, Py H); 11.3 (s, NH).

EXAMPLE 11

1,5-dihydro1,5-dioxo-7-fluoro-4H- 1!-benzopyrano 3,4-b!pyridine-2-carboxylic acid ##STR16##

A solution of ethyl-1,5-dihydro-1,5-dioxo-7-fluoro-4H- 1!-benzopyrano 3,4-b!-pyridine-2-carboxylate (1.70 g; 5.606 mmole) in a 10% aqueous sodium hydroxide solution (22 ml) was heated for 90 minutes at the boiling temperature and then it was boiled for about 5 minutes with active carbon. In the filtrate the acid was precipitated with a 10% aqueous hydrochloric acid solution (up to pH 2-3) and the cooled solution was left to stand for a few hours at +4° C. The obtained light yellow precipitate of the acid (1.50 g; 97%) was recrystallized from an ethyl acetate/ethanol mixture (1:1) or from N,N-dimethylformamide. M.p. >300° C.

Analysis: calculated for C₁₃ H₆ FNO₅ C 56.74; H 2.20; N 5.09. found C 56.52; H 1.84; N 5.11. .sup. 1H-NMR (TFA)δ/ppm: 7.3-7.4 (m, 3 Ar H); 8.7 (m, Py H); 9.2 (s, NH); 11.3 (s, COOH).

EXAMPLE 12

4,5-dihydro-4,5-dioxo-4H- 1!-benzopyrano 4,3-b!pyridine-3-carboxylic acid ##STR17##

A solution of ethyl-4,5-dihydro-4,5-dioxo-4H- 1!-benzopyrano 4,3-b!pyridine-3-carboxylate (1.90 g; 6.661 mmole) in 1M sodium hydroxide (50 ml) was heated for 90 minutes at boiling temperature and then shortly boiled with active carbon, it was filtered and the filtrate was acidified with a 10% aqueous hydrochloric acid solution (up to pH 2-3) and the acid was precipitated (1.54 g; 95%). M.p.>300° C.

Analysis: calculated for C₁₃ H₇ NO₅ C 60.70; H 2.74; N 5.45found C 60.37; H 2.43; N 5.51. ¹ H-NMR (DMSO-d₆)δ/ppm: 7.5 (d, H7); 7.8 (t, H9); 8.4 (d, H10); 8.7 (m, H8,Py H); 9.2 (s, NH); 11.3 (s, COOH). m/z: 256 (M⁻), 240, 239, 223, 212, 211, 183, 120, 82.

EXAMPLE 13

1,5,8-trihydro-1,5,8-trioxo-4,1 1H- 1!-benzopyrano 3,4-b !7,6-c!dipyridine-2,9-dicarboxylic diacid ##STR18##

It was prepared according to the method disclosed in Example 12 starting from diethyl-1,5,8-trihydro-1,5,8-trioxo-4,11H- 1!-benzopyrano 3,4-b! 7,6-c!dipyridine-2,9-dicarboxylate (0.90 g; 121 mmole). Duration of the reaction: 45 minutes. The obtained acid was of yellow brown colour (0.45 g; 58%). M.p. >300° C.

Analysis: calculated for C₁₇ H₈ N₂ O₈ C 55.44; H 2.19; N 7.61. found C 55.22; H 2.58; N 7.50. .sup. 1H-NMR (DMSO-d₆)δ/ppm: 7.1-9.5 (m, Ar H, Py H); 12.3 (d, 2 NH); 14.8 (s, COOH); 15.4 (s, COOH). m/z: 368 (M⁺), 341, 264, 256, 213, 198, 188, 156, 137, 129, 91, 81, 69.

EXAMPLE 14

4,7-dihydro-4,7-dioxo-1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylic acid ##STR19##

It was prepared according to the method disclosed in Example 11 starting from ethyl-4,7-dihydro-4,7-dioxo-1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylate (1.10 g; 3.856 mmole). Duration of the reaction: 3 hours. A light yellow precipitate of the acid (0.84 g; 85%) was obtained. M.p. >300° C.

Analysis: calculated for C₁₃ H₇ NO₅ C 60.70; H 2.74; N 5.45. found C 60.37; H 2.80; N 5.76. m/z: 258 (M⁺), 254, 249, 213, 151, 138, 125, 109, 98, 74, 62.

EXAMPLE 15

4,7-dihydro-4,7-dioxo-8-hydroxy-1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylic acid ##STR20##

It was prepared according to the method disclosed in Example 12 starting from ethyl-4,7-dihydro-4,7-dioxo-8-hydroxy-1H- 1!-benzopyrano 6,7-b!pyridine-3-carboxylate (2.83 g; 9.394 mmole). Duration of the reaction: 3 hours. A yellow precipitate of the acid (2.13 g; 83%) was obtained. M.p. >300° C. .sup. 1H-NMR (DMSO-d₆)δ/ppm: 7.6-8.7 (m, Ar H); 9.4 (s, Py H); 13.4 (s, NH); 15.2 (s, COOH). m/z: 273 (M⁺), 256, 239, 229,181, 125, 114, 95, 73.

EXAMPLE 16

1,7-dihydro-1,7-dioxo-9-methyl-4H- 1!-benzopyrano 6,7-b!pyridine-2-carboxylic acid ##STR21##

It was prepared according to the method disclosed in Example 11 starting from ethyl-1,7-dibydro-1,7-dioxo-9-methyl-4H- 1!-benzopyrano 6,7-b!pyridine-2-carboxylate (3.40 g; 0.011 nmole). Duration of the reaction: 20 minutes. The obtained precipitate of gray white colour was recrystallized from N,N-dimethylformamide (2.32 g; 75%).

Analysis: calculated for C₁₄ H₉ NO₅ xC₃ H₇ NO C 59.30; H 4.68; N 8.14. found C 59.50; H 4.61; N 7.81. ¹ H-NMR (DMSO-d₆)δ/ppm: 1.9 (s, CH₃); 6.3 (s, H8); 7.6 (d, H5); 8.0 (s, H10);

9.0 (s, Py H); 13.2 (bs, NH); 14.9 (s, COOH).

EXAMPLE 17

1,7-dihydro-1,7-dioxo-9-(trifluromethyl)-4H- 1!-benzopyrano 6,7-b!pyridine-2-carboxylic acid ##STR22##

It was prepared according to the method disclosed in Example 12 starting from ethyl-1,7-dihydro-1,7-dioxo-9-(trifluromethyl)-4H- 1!-benzopyrano (6,7-b!pyridine-2-carboxylate (1.40 g; 3.963 mmole). Duration of the reaction: 2 hours. The obtained acid was recrystallized from the N,N-dimethylformamide/ethanol mixture (1.28 g; 99%). M.p. >300° C.

Analysis: calculated for C₁₄ H₆ F₃ NO₅ C 51.70; H 1.86; N 4.31. found C 51.48; H 1.82; N 4.27. ¹ H-NMR (DMSO-d₆)δ/ppm: 7.2 (s, H8); 7.8 (s, H5); 8.6 (s, H10); 9.0 (s, Py H);

13.4 (bs, NH); 14.5 (bs, COOH).

EXAMPLE 18

1,5-dibydro-1,5-dioxo-7-hydroxy-4H- 1!-benzopyrano 7,8-b!pyridine-2-carboxylic acid ##STR23##

It was prepared according to the method disclosed in Example 13 starting from ethyl-1,5-dihydro1,5-dioxo-7-hydroxy-4H- 1!-benzopyrano 7,8-b!pyridine-2-carboxylate (2.12 g; 7.037 mmole). Duration of the reaction: 3 hours. A green brown acid (1.27 g; 66%) was obtained. M.p. >300° C. ¹ H-NMR (DMSO-d₆)δ/ppm: 7.1-7.8 (m, Ar H, Py H); 8.6 (s, OH); 10.6 (s, NH); 15.2 (s, COOH). m/z: 273 (M⁺), 212, 179, 81, 79, 61, 59, 45, 43. 

We claim:
 1. A coumarin quinolone carboxylic acid wherein the pyridone system is fused in 3,4-, 6,7- and 7,8-positions of the coumarin system, of the formula I ##STR24## wherein R¹ R² =--NHCH=C(CO₂ R⁶)CO, R³ =NO₂ or NH₂,R⁴ =R⁵ =H, R⁶ =H or C₂ H₅ ;R¹ R² =--NHCH=C(CO₂ R⁶)CO, R³ =R⁴ =H,R⁵ =F, R⁶ =H or C₂ H₅ ; R¹ R² =--CO(CO₂ R⁶)C=CHNH, R³ =R⁴ =R⁵ =H, R⁶ =H or C₂ H₅ ; R¹ R² =R³ R⁴ =--NHCH=C(CO₂ R⁶) CO, R⁵ =H, R⁶ =H or C₂ H₅ ; R¹ =H or OH, R² =R⁵ =H, R³ R⁴ =--NHCH=C(CO₂ R⁶) CO, R⁶ =H or C₂ H₅ ; R¹ =OH, R² =R³ =H, R⁴ R⁵ =--CO(CO₂ R⁶) C=CHNH, R⁶ =H or C₂ H₅ ; R¹ =R⁵ =H, R² =CH₃ or CF₃, R³ R⁴ =--CO(CO₂ R⁶)C=CHNH, R⁶ =H or C₂ H₅,or a pharmaceutically acceptable salt thereof.
 2. The compound of the formula I according to claim 1, wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =R⁴ =H, R⁵ =F.
 3. The compound of the formula I according to claim 1, wherein R¹ R² =--CO(CO₂ C₂ H₅)C=CHNH, R³ =R⁴ =R⁵ =H.
 4. The compound of the formula I according to claim 1, wherein R¹ R² =R³ R⁴ =--NHCH=C(CO₂ C₂ H₅)CO, R⁵ =H.
 5. The compound of the formula I according to claim 1, wherein R¹ =H, R² =R⁵ =H, R³ R⁴ =--NHCH=C(CO₂ C₂ H₅)CO.
 6. The compound of the formula I according to claim 1, wherein R¹ =OH, R² =R⁵ =H, R³ R⁴ =--NHCH=C(CO₂ C₂ H₅)CO.
 7. The compound of the formula I according to claim 1, wherein R¹ =R⁵ =H, R² =CH₃, R³ R⁴ =--CO(CO₂ C₂ H₅)C=CHNH.
 8. The compound of the formula I according to claim 1, wherein R¹ =R³ =R⁵ =H, R² =CF₃, R⁴ =--NHCH=C(CO₂ C₂ H₅)₂.
 9. The compound of the formula I according to claim 1, wherein R¹ =OH, R² =R³ =H, R⁴ R⁵ =--CO(CO₂ C₂ H₅)C=CHNH.
 10. The compound of the formula I according to claim 1, wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =NO₂, R⁴ =R⁵ =H.
 11. The compound of the formula I according to claim 1, wherein R¹ R² =--NHCH=C(CO₂ C₂ H₅)CO, R³ =NH₂, R⁴ =R⁵ =H.
 12. The compound of the formula I according to claim 1, wherein R¹ R² =--NHCH=C(CO₂ H)CO, R³ =R⁴ =H, R⁵ =F.
 13. The compound of the formula I according to claim 1, wherein R¹ R² =--CO(CO₂ H)C=CHNH, R³ =R⁴ =R⁵ =H.
 14. The compound of the formula I according to claim 1, wherein R¹ R² =R³ R⁴ =--NHCH=C(CO₂ H)CO, R⁵ =H.
 15. The compound of the formula I according to claim 1, wherein R¹ =H, R² =R⁵ =H, R³ R⁴ =--NHCH=C(CO₂ H)CO.
 16. The compound of the formula I according to claim 1, wherein R¹ =OH, R² =R⁵ =H, R³ R⁴ =--NHCH=C(CO₂ H)CO.
 17. The compound of the formula I according to claim 1, wherein R¹ =R⁵ =H, R² =CH₃, R³ R⁴ =--CO(CO₂ H)C=CHNH.
 18. The compound of the formula I according to claim 1, wherein R¹ =R³ =R⁵ =H, R² =CF₃, R⁴ =--NHCH=C(CO₂ H)₂.
 19. The compound of the formula I according to claim 1, wherein R¹ =OH, R² =R³ =H, R⁴ R⁵ =--CO(CO₂ H)CHNH.
 20. The compound of claim 1 whereinR¹ R² =--NHCH(CO₂ R⁶))CO,R³ =NO₂ or NH₂, R⁴ =R⁵ =H, R⁶ =H or C₂ H₅ ; or R¹ R² =--NHCH(CO₂ R⁶)CO, R³ =R⁴ =H, R⁵ =F, R⁶ =H or C₂ H₅ ; or R¹ R² =--CO(CO₂ R⁶)CHNH, R³ =R⁴ =R⁵ =H, R⁶ =H or C₂ H₅. 